Wall-sealed battery casing and sealed primary sodium-halogen battery

ABSTRACT

A wall-sealed battery casing and a sealed primary sodium-halogen battery are disclosed wherein the casing includes an open ended inner vessel of a solid crystalline ion-conductive material, an electronic conductor within the interior of the inner vessel, two outer opposed open ended metallic portions each with an additional opening surrounding the inner vessel, the two opposed vessel portions sealed together and to the outer wall of the inner vessel, and a fill tube associated with the respective additional opening in each outer vessel portion. A sealed primary sodiumhalogen battery has the above type of wall-sealed casing with a solid sodium containing ion-conductive inner vessel, a sodium anode and a cathode of a halogen in conductive material. The anode and cathode are positioned, respectively, in either the inner vessel or between the inner vessel and the outer vessel portion adjacent the closed end of the inner vessel.

United States Patent [1 1 Dubin et a].

[ WALL-SEALED BATTERY CASING AND SEALED PRIMARY SODIUM-HALOGEN BATTERY[75] inventors: Robert R. Dubin; William L.

Mowrey; William A. Gilhooley, all of Schenectady, NY.

[73] Assignee: General Electric Company,

Schenectady, NY.

[22] Filed: May 28, 1974 [2]] Appl. No.: 474,036

Related U.S. Application Data 7 [62] Division of Ser. No. 239,890, March31, 1972.

[52] U.S. 136/83 R; 136/86 A May 6,1975

Primary Examiner-John H. Mack Assistant ExaminerC. F. Lefevour Attorney,Agent, or FirmPaul R. Webb, ll; Joseph T. Cohen; Jerome C. Squillaro[57] ABSTRACT A wall-sealed battery casing and a sealed primarysodium-halogen battery are disclosed wherein the casing includes an openended inner vessel of a solid crystalline ion-conductive material, anelectronic conductor within the interior of the inner vessel, two outeropposed open ended metallic portions each with an additional openingsurrounding the inner vessel, the two opposed vessel portions sealedtogether and to the outer wall of the inner vessel, and a fill tubeassociated with the respective additional opening in each outer vesselportion. A sealed primary sodiumhalogen battery has the above type ofwall-sealed casing with a solid sodium containing ion-conductive innervessel. 21 sodium anode and a cathode of a halogen in conductivematerial. The anode and cathode are positioned, respectively, in eitherthe inner vessel or between the inner vessel and the outer vesselportion adjacent the closed end of the inner vessel.

1 Claim, 2 Drawing Figures WALL-SEALED BATTERY CASING AND SEALED PRIMARYSODIUM-HALOGEN BATTERY This is a division of application Ser. No.239.890. filed Mar. 3|. W72.

This invention relates to a wall-sealed battery casing and to sealedprimary batteries and. more particularly. to such wall scaled batterycasings and batteries cmploying an anode of sodium. sodium as an amalgamor sodium in a non-aqueous electrolyte and a cathode of a halogen inconductive material.

Sodium-sulfur cells. which operate at elevated temperatures. are knownin the prior art as. for example. described in Kummer et al US. Pat. No.3.404.036 issued Oct. l. [968 under the title Energy Conversion DeviceComprising a Solid Crystalline Electrolyte and a Solid Reaction ZoneSeparator. The solid crystalline ionconductive electrolyte in theabove-mentioned sodium sulfur battery can be sodium beta-alumina.

Sodium amalgam-oxygen fuel cells are known in the prior art as. forexample. described in Eidensohn US. Pat. No. 3.057.946 issued Oct. 9.1962 under the title "Fuel Cell System. A sodium amalgam is flowed overthe face of a metallic plate within an aqueous solution of sodiumhydroxide to provide the anode.

ln copending patent application Ser. No. 153.364. filed June 15. l97 l.entitled "Sealed Primary Sodium- Bromine Battery in the names of StephanP. Mitoff and Fritz G. Will. there is described and claimed a sealedprimary sodium-bromine battery employing a sodium type anode and acathode of bromine in conductive material within a casing and separatedby a solid sodium ion-conductive electrolyte.

ln U.S. Pat. No. 3.793.080. in the name of Heinrich .l. Hess andentitled Sealed Primary Sodium-Halogen Battery with Bromine-IodineMixture. there is described and claimed a sealed primary sodium-halogenbattery employing a sodium type anode and a cathode ofa mixture ofbromine and iodine in conductive material.

ln copcnding patent application Ser. No. 230.864. filed Mar. l. I972.now abandoned. entitled Battery Casing and Sealed Primary Sodium-HalogenBattery in the names of Heinrich J. Hess and Fritz G. Will. there isdescribed and claimed a battery casing and a sealed primarysodium-halogen battery wherein a cover with an opening is sealed toupper ends of an inner casing of a solid sodium ion-conductive materialand an outer metallic casing. The above three copending patentapplications are assigned to the same assignee as the presentapplication.

Our present invention is directed to providing a wallsealed batterycasing and a sealed primary sodiumhalogen battery operable attemperatures of 48 to l C in which the casing has a sealing surface areawhich is independent ofthe wall thickness of the inner vessel and inwhich the battery allows larger currents to be drawn than from a batteryof equivalent size employing a solid electrolyte disk.

The primary objects of our invention are to provide an improvedwall-sealed battery casing and a low temperature primary battery whichhas a zero selfdischarge rate. high cell voltage and high energydensity.

In accordance with one aspect of our invention. a wall-sealed batterycasing includes an open ended inner vessel of a solid crystallineion-conductive material. an

electronic conductor within the interior of the inner vessel. two outeropposed open ended metallic vessel portions each with an additionalopening surrounding the inner vessel. the two opposed vessel portionssealed together and to the outer wall of the inner vessel. and a filltube associated with the respective additional opening in each outervessel portion.

These and various other objects. features and advantages of theinvention will be better understood from the following description takenin connection with the accompanying drawing in which:

FIG. 1 is a sectional view ofa wall-sealed battery casing made inaccordance with our invention; and

FIG. 2 is a sectional view of a wall-sealed battery made in accordancewith our invention.

In FIG. 1 of the drawing. there is shown generally at it) a wall-sealedbattery casing embodying our invention which has an inner casing ll of asolid crystalline ionconductive material with one open end 12. Anelectronic conductor 13 is positioned within the interior of innercasing H and extending outwardly through open end 12 of casing 11. Twoouter opposed metallic vessel portions l4 and 15 each have open end 16and 17. respectively. and an additional opening 18 and [9. respectively.in each opposite closed end 20 and Zl. respectively. While each openingl8 and I9 is shown in the opposite closed end 20 and 21, such openingcan be located at other points in vessel portions 14 and IS. Metallicfill tubes 22 and 23 are affixed to each closed end 20 and 21 and incommunication with openings l8 and I9. respectively. and an outwardlyextending flange 24 and an inwardly extending flange 25 are affixed tothe respective vessel portions l4 and I5 at their open ends 16 and 17.Metallic vessel portions l4 and I5 surround inner casing I]. A sodiumand halogen resistant glass 26 seals flanges 24 and 25 together andseals the vessel portions 14 and 15 to the outer wall of inner vesselll. Electronic conductor [3 is shown as affixed to the inner surface ofclosed end 20 of vessel portion 14.

In FIG. 2 of the drawing. there is shown a sealed primary sodium-halogenbattery embodying our invention which battery includes theabove-described wall-sealed battery casing shown in H6. I. An anode 27is positioned preferably in inner vessel ll. Anode 27 which is shown assodium metal. is selected from the class consisting of sodium. sodium asan amalgam. or sodium in a non-aqueous electrolyte. A cathode 28 of ahalogen in conductive material is positioned preferably within outervessel portion 15 adjacent the closed end of inner vessel 1 1. After thebattery is filled. the associated fill tubes 22 and 23 are closed. forexample. by welding at 29 and 30. respectively. It will be appreciatedthat the locations of the anode and cathode can be reversed. Theresulting structure is a sealed sodium halogen battery.

We found that a wall-sealed battery casing could be formed bypositioning an inner vessel of a crystalline ionconductive materialhaving an open end within two outer opposed open ended metallic vesselportions of a suitable. chemically stable metal such as niobium ortantalum. Each metallic vessel portion has an additional opening whichis preferably in each opposite closed end.

The solid crystalline ion-conductive materials include variousion-conductive materials with oxides of sodium. lithium. potassiumhaving ion conductivity or mixtures of these oxides. Additionally. onevessel portion can be made of Kovar alloy for use adjacent the sodiumanode in a battery. Each outer metallic vessel portion has an oppositelydirected flange affixed to its open end. Prior to positioning the outervessel portions. a washer of a suitable sodium resistant glass. such asKimble Glass No. N-SlA is placed around the outer surface of the innervessel at the proposed sealingjunction. Such glass is also resistant tohalogens. Other suitable sodium and halogen resistant glasses includeCorning Glass Nos. 7056 and 7052. General Electric ompany Glass No. ll 3and Sovirel Glass No. 747. The fill tubes are shown as a unitarystructure with each respective outer vessel portion. However. such filltubes can also be separate parts and sealed to each outer vesselportion. for example. by welding. An electronic conductor in the form ofa thin wire is welded to the inner surface of the closed end of theassociated outer vessel portion. The wire is made of a chemically stablemetal. such as nickel.

We found that a helium leak tight wall seal can be formed by placing theabove-mentioned glass washer around the inner washer between the opposedflanges of the outer vessel portions. The components are then placed ina closely confining graphite crucible equipped with a weight to compressthe sealing glass during heating. The crucible is then placed in aretort which is continuously purged with high purity argon gas. Theretort. which contains a thermocouple to assure accurate temperaturecontrol. is heated to l.050 C for l0 minutes in a hydrogen furnace. Suchhelium leak tight wall seals can also be made in inert atmospheres usingheating techniques. such as radio frequency heating. resistance heating.and laser heating. The resulting structure is a wall-sealed batterycasing.

We found that a sealed primary sodium-halogen battery could be formed byemploying the above described wall-sealed battery casing. Further. thetwo outer metallic vessel portions can also have opposite closed endswithout openings and associated fill tubes. if this structure isemployed. it will be appreciated that the respective inner vessel andouter metallic vessel portion adjacent the closed end of the innervessel will have to be filled with anode and cathode materials prior toassembly. The solid crystalline ion-conductive materials for the innervessel of the battery is solid sodium containing ion-conductivematerial. Sodium ionconductivity is necessary in the operation of thebattery. Sodium containing" includes sodium oxide. and mixtures ofsodium oxide with other metallic oxides where there is sodium ionconductivity. The anode may consist of sodium. a sodium amalgam orsodium in a non-aqueous organic electrolyte. The anode is positionedpreferably within the inner vessel by filling the inner vessel throughits associated fill tube. Additionally. the portion of the inner vesselwith the open end can be shortened to provide a larger volume reservoirfor the electrode material. Such structure can also be employed in thebattery casing shown in FIG. I. When the sodium is in the form ofasodium amalgam its range of compositions is from about 95% sodium andmercury by weight to about 35% sodium and 65% mercury. For the fullycharged state of the cell. the amalgam composition is preferably high insodium. Cells using sodium amalgam cannot be used efficiently attemperatures below 2l.5 C due to complete freezing of the amalgam.

The use of non-aqueous electrolytes permits battery operation to muchlower temperatures as determined by the freezing point of thenon-aqueous electrolyte. The preferred electrolyte is propylenecarbonate in S which a sodium halide salt is dissolved. This electrolytepermits battery operation down to 48 C. After the inner casing has beenfilled with the anode material the fill tube is closed and sealed. forexample. by welding.

The cathode is positioned preferably within the outer metallic vesselportion adjacent the closed end of the inner vessel through theassociated fill tube and is in contact with both inner and outervessels. The cathode comprises a halogen in conductive material. Thehalogen is selected from the class consisting of bromine. and a mixtureof bromine and iodine with from 5 to 60 weight percent iodine.

The electrically conductive materials for the bromine include a porousmatrix of carbon felt. a porous matrix of foam metal. an aqueouselectrolyte. or a nonaqueous electrolyte. Preferred aqueous electrolytesare solutions of sodium halide salts. Preferred non-aqueous electrolytesare solutions of sodium halide salts in propylene carbonate.

The electrically conductive materials for the mixture of bromine andiodine include a porous matrix of carbon felt. a porous matrix of foammetal. dissolved small amounts of additives. such as NaCl. NaBr. KCl.AlCl AlBr POCl etc.. or a combination of both matrix and additive.

After the halogen in conductive material cathode has been positionedwithin the outer metallic vessel portion. the associated fill tube isclosed. for example. by welding. This results in a sealed primarysodiumhalogen battery.

Examples of wall-sealed battery casings and sealed primarysodium-halogen batteries made in accordance with our invention are setforth below:

EXAMPLE I A wall-sealed battery casing was assembled as above describedand as shown in PK]. 1. The inner vessel was made of sodium beta-aluminahaving an open end. The vessel had a length of 720 mils. an outerdiameter of 200 mils, an inner diameter of [60 mils. and a wallthickness of mils. The two opposed open ended metallic vessel portionswere spun from tantalum sheet to a final wall thickness of 0.0l inch.The first vessel portion had a length of 460 mils. an outer diameter of320 mils. and a 0.045 inch inwardly extending flange. The second vesselportion had a length of 300 mils. an outer diameter of 250 mils. and a0.045 inch outwardly extending flange. The additional opening in eachouter vessel was 125 mils. A 0.005 inch nickel wire was spot welded tothe interior surface of the second vessel portion to provide theelectronic conductor for the inner vessel. A 15 mil thick tantalum filltube was electron beam welded to the closed end of each outer vessel tocommunicate with the additional opening in each outer vessel. A 0.06inch glass washer of Kimble glass N-S l A with a 0.32 inch outerdiameter was positioned around the outer wall of the inner vessel at adistance from both ends of the inner vessel. The two outer vesselportions were positioned around the inner vessel with the flanges at therespective open ends in contact with the opposite surfaces of the glasswasher. The first vessel portion with the smaller outer diameter ispositioned around the portion of the inner vessel with the open end.while the second vessel portion with the larger outer diameter ispositioned around the portion of the inner vessel with the closed end.The nickel wire is inserted in the chamber defined by the inner vessel.

The above components were placed in a closely con fining graphitecrucible equipped with a weight to compress the sealing glass duringheating. The crucible was then placed into a retort which wascontinuously purged with high purity argon gas. The retort. whichcontained a thermocouple to assure accurate temperature control. washeated to l.050 C for l minutes in a hydrogen furnace. After the batterycasing was removed. the wall seal was 0.040 inch thickness. Thestructure was tested and found to be helium leak tight. The resultingdevice was a wall-sealed battery casing.

EXAMPLE 2 A partially sealed primary sodium-bromine battery wasassembled by employing the wall-sealed battery casing described above inExample 1. The inner vessel EXAMPLE 3 The battery of Example 2 showed anopen circuit voltage of 3.70 volts. The short circuit current was 30milliamperes. At room temperature. this battery exhibitcd the followingpolarization behavior which is shown below in Table I.

TA B LE l (urrent- Current Density Volts Milliamperes ma/cm" EXAMPLE 4 Asealed primary sodium-bromine battery is assembled by employing thewall-sealed battery casing described above in Example I. The innervessel is filled with sodium amalgam of 90 weight percent sodium and I0weight percent mercury through the associated fill tube after which thefill tube is sealed by welding. The outer vessel portion adjacent theclosed end of the inner vessel is filled through the associated filltube with weight percent bromine in 25 weight percent propylenecarbonate after which the fill tube is sealed by welding. The resultingstructure is a sealed primary sodium-halogen battery. At roomtemperature this battery has an open circuit voltage of 3.70 volts. Theshort circuit current is 30 milliamperes.

While other modifications of the invention and variations thereof whichmay be employed within the scope of the invention have not beendescribed. the invention is intended to include such as may be embracedwithin the following claims.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. A wall-sealed battery casing comprises an open ended inner vessel ofa solid crystalline ionconductive material. an electronic conductorwithin the interior of the inner vessel and extending outwardly throughthe open end of the vessel. two outer opposed open ended metallic vesselportions each with an additional opening surrounding the inner vessel.each outer vessel portion has an oppositely extending flange at its openend. and a sodium and halogen resistant glass seals the adjacent flangestogether and seals the outer vessel portions to the outer vesselportions to the outer wall of the inner vessel. a fill tube affixed toeach additional opening. the electronic conductor affixed to theassociated outer metallic vessel portion. and the two outer metallicvessel portions sealed together and to the outer wall of the innervessel.

1. A WALL-SEALED BATTERY CASING COMPRISES AN OPEN ENDED INNER VESSEL OFA SOLID CRYSTALLINE IONCONDUCTIVE MATERIAL, AN ELECTRONIC CONDUCTORWITHIN THE INTERIOR OF THE INNER VESSEL AND EXTENDING OUTWARDLY THROUGHTHE OPEN END OF THE VESSEL, TWO OUTER OPPOSED OPEN ENDED METALLIC VESSELPORTIONS EACH WITH AN ADDITIONAL OPENING SURROUNDING THE INNER VESSEL,EACH OUTER VESSEL PORTION HAS AN OPPOSITELY EXTENDING FLANGE AT ITS OPENEND, AND A SODIUM AND HALOGEN RESISTANT GLASS SEALS THE ADJACENT FLANGESTOGETHER AND SEALS THE OUTER VESSEL PORTIONS TO THE OUTER VESSELPORTIONS TO THE OUTER WALL OF THE INNER VESSEL, A FILL TUBE AFFIXED TOEACH ADDITIONAL OPENING, THE ELECTRONIC CONDUCTOR AFFIXED TO THEASSOCIATED OUTER VESSEL PORTION,